<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title>Document</title>
	</head>
	<body>
		<script type="text/javascript">
			function calculate(method,...nums){
				let result;
				if(!method||nums.length==0){
					alert("请输入参数");
					return;
				}
				if(method=='*'){
					result=1;
					for(let i=0;i<nums.length;i++){
						result*=nums[i];
					}
				}else if(method=='+'){
					result=0;
					for(let i=0;i<nums.length;i++){
						result+=nums[i];
					}
				}
				alert(result);
			}
			calculate("+",1,2);//3
			calculate("*",1,2,3,4,5);//15
			calculate("*",1,2,3);//6
			calculate("*",1,2,3,4,5);//120
		</script>
	</body>
</html>